Traditional Buddhist medical science researchs are mainly focus on the analysis of Buddhist Struas which contained medicine knowledge, and followed the view points of either Western, Chinese or Tibetan medical systems to exam these knowledge. In this paper, the author offers a different approach of Buddhist medical science study, which are through ethnolmedicaine system and its etiology, diagnostics, therapeutics and preventive medicine. These new social and culture angles help us to understanding the relationship between the idea and behaviors of medical treatment in Buddhist ethnomedicine. In this cases study of Achi Chokyi Roma’s Dvidination, which belongs to Drikung Kagyu School of Tibetan Buddhism, the author presents the ethnomedicine view base on the investigation of Achi Chokyi Droma’s divinatory sentences. Finding out that comparing to Chinese Buddhism, the Tibetan Buddhist Divinations are highly developed, much more riches in the methods, the deities, divinatory sentences and contents. The Tibetan Buddhist Divination is not limited in Buddhist science, but deeply combined with the essential values and local medical custom of Tibetan. It notice Tibetan medical system, but go beyond it to provide the body and mind caring function directly or indirectly. Instead of giving the direct medicine prescription as Chinese medical lots, the divination of Achi emphasizes the doctor-patient’s harmonious relationship, through the interaction between ‘Human being and holy being, such as Buddhist and Bodhisattvas’; and ‘individual and Master’. It shows the spirit and psychology trust in Tibetan Buddhist history inheritance, and the symbols of both culture and belief in Tibetan society. The divination of Achi is not a spiritual placebo, it’s one kind of special medical treatment which suits the local circumstances and meets the social demand. Therefore, it should be esteemed and given a suitable evaluation.